One thing you could do is give each combatant 3 shields and a weapon of their choice and have them fight until one party's shields are all broken, one party is unconscious or dead (youre breaking shields, it would happen) or one party surrenders.

Each shield could be represented by a certain hit point threshold (arbitrarily, 10 hp worth of damage) and any other armor they happen to have is perfectly allowed, since youre not actually trying to kill each other. From there, you can work out a system of honor for recognizing when youre beaten versus valiantly standing your ground in the face of certain loss, or even losing in the face of certain victory.